Quantitative Refractometric-Spectrophotometric Analysis of Oil Solutions of Vitamins A and E

A refractometric-spectrophotometric method is proposed for routine analyses for vitamins A and E in oil solutions, which is 3-4 times less time-consuming than HPLC. The determination procedure includes measurements of the refractive index n _D ²⁰ of samples and optical density of their solutions in hexane at 325 nm.     

Kinetics of Methyl Iodide Tribosorption on the Solid-Phase Salt KI

It was found that the tribosorption of methyl iodide from the gas phase of a closed reactor onto a matrix of KI is described by the rate equation for a reversible first-order reaction v _g – v _{, g} = mv _ts ^* exp(–_td D _sp), where v _g and v _{, g} are, respectively, the current and equilibrium amounts of methyl iodide in the gas phase; v _ts ^* is the equilibrium amount of methyl iodide tribosorbed per gram of salt; m is the mass of potassium iodide; _td is a constant, which characterizes the efficiency of tribodesorption (_td = 0.011 ± 0.005 g/J); and D _sp is the specific dose of mechanical energy absorbed by the KI powder. The value of v _ts ^* monotonically increased with increasing equilibrium partial pressure of methyl iodide and reached a maximum value of 25 mol/g. The lower limit of the constant _td, which characterizes the efficiency of tribosorption, was estimated at 0.1 g/J.     

Electron conduction in the phenylhydrazines

Kinetic studies have been made on the conduction, which is compared with the values deduced from dissociation constants and shifts in the NH₂ stretching frequencies. The high conductivity coefficient in reaction with p-toluene sulfobromide is ascribed to a hydrogen bond in the transition complex.Read at the meeting of the extended plenum of the council of the Academy of Sciences of the Ukrainian SSR on Theories of Chemical Structure, Kinetics, and Reactivity, 7 December 1966, Kiev.     

Effect of pressure on the rotational mobility of spin probes in polymers

The effects of pressure on the rotational mobility of three nitroxyl radicals (spin probes) in natural rubber, polyethylene, and butadiene-nitrile rubber SRN-26 have been studied. The activation volumes, activation energies, and pre-exponential factors of spin probe rotation at constant pressure and volume have been determined. The activation volumes of probe rotation (20–70 cm³/mol) increase with increasing size of radicals and differ insignificantly from the activation volumes of the β-relaxation process. In the polar polymer SRN-26, the activation volumes of rotation of radicals are appreciably more than in the nonpolar polymers, natural rubber and polyethylene. These features are apparently due to different volumes of the kinetic chain segment controlling probe rotation. The activation volumes of radical rotation around different molecular axes differ significantly. The activation energy of probe rotation at constant volume is appreciably less than at constant pressure. It has also been shown that the energy necessary for the formation of a fluctuation hole is the main factor that determines temperature dependence of the rotational mobility of low-molecular particles in the polymer.     

Theoretical analysis of the structure and intramolecular dynamics of imidazolium halide and N-methylimidazolium halide ion pairs

A plant for the theoretical analysis of the structure and intramolecular dynamics of ion pairs of organic salts based on the combined use of the results of quantum-chemical calculations and molecular mechanics has been proposed. The potential-energy surfaces of the interionic interactions in imidazolium halide and N-methylimidazolium halide ion pairs have been investigated, and the equilibrium geometric parameters and frequencies of the interionic vibrations have been determined. It has been established that these ion pairs should be classified as stereochemically nonrigid molecules.Deceased.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 5, pp. 522–529, September–October, 1985.